The Milky Way meets a sausage

Eight to ten billion years ago, thus, in its youth, our Milky Way apparently had a fateful encounter: it crossed paths with another, significantly smaller galaxy. The researchers who discovered this gave the smaller galaxy the name “Sausage Galaxy,” but this is perhaps a little unfair, because in reality it had a similar elliptical shape as the Milky Way.
The name “Sausage” came from the way the collision was proven. To do this, astronomers examined the distribution of velocities of the stars in the Milky Way. This showed that a sausage-shaped group of stars with similar patterns of motion is moving through our Milky Way – and these stars are the remnants of the former dwarf galaxy.

It wasn’t especially small, however. It had a mass of approximately ten billion Suns (Miky Way: 900 billion) and was even big enough to drag along a pair of open star clusters. The collision must have torn quite a hole in the disk of the Milky Way, and probably led to the formation of its central bulge.

Artist’s rendering of the two galaxies before the collision (picture: V. Belokurov (Cambridge, UK); Based on image by ESO/Juan Carlos Muñoz)


If you look at the distribution of star motions in the Milky Way, you can see the sausage shape of the stars that originated from the other galaxy (picture: V. Belokurov (Cambridge, UK) und Gaia/ESA)

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  • BrandonQMorris
  • Brandon Q. Morris is a physicist and space specialist. He has long been concerned with space issues, both professionally and privately and while he wanted to become an astronaut, he had to stay on Earth for a variety of reasons. He is particularly fascinated by the “what if” and through his books he aims to share compelling hard science fiction stories that could actually happen, and someday may happen. Morris is the author of several best-selling science fiction novels, including The Enceladus Series.

    Brandon is a proud member of the Science Fiction and Fantasy Writers of America and of the Mars Society.